Water purification system for dental instrument

ABSTRACT

A cartridge system for purifying water supplied to a dental unit and dynamic dental instrument has at least one disposable cartridge element having an activated charcoal resin and an iodinated anionic exchange resin containing a continuous fixed-rate release iodinated resin I.sub.(n). Iodine is released from the iodinated resin at a specified and consistent rate as water passes through the resin to maintain dental unit water purity. The activated charcoal resin functions to remove chlorine from incoming water to prevent chlorine reaction with iodine. The cartridge is installed in the water supply tubing at the point of connection to a water supply system. Tubing having inner surfaces passivated with iodine is connected to the downstream end of the cartridge. The cartridge is the principal water purification source and reinforces an existing water purification system. The cartridge is used to provide microbiologically pure water to the dental unit and to prevent back contamination to the water supply system and tubing biofilm. The iodinated biocidal resin neutralizes and kills disease causing bacteria, viruses and protozoa as water passes through the cartridge providing microbiologically pure water to the dynamic dental instrument. Aspirated microbes are killed by residual iodine eluted from the cartridge and are prevented from traveling back beyond the cartridge. The residual iodine also maintains the passivated condition of the tubing through a state of equilibrium between the tubing and water located therein creating a biostatic condition within the tubing to resist microorganism colonization and biofilm on the tubing.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. application Ser. No.08/097,162, filed Jul. 23, 1993, now U.S. Pat. No. 5,370,534.Application Ser. No. 08/097,162 is a continuation-in-part of U.S.application Ser. No. 07/973,454 filed Nov. 9, 1992, now U.S. Pat. No.5,230,624.

FIELD OF THE INVENTION

The invention relates to modern dental units containing a water supplysystem that provides coolant and rinse water to the highspeed dentalhandpiece, ultrasonic scaler and air/water syringe and methods of waterpurification for dental units.

BACKGROUND OF THE INVENTION

All modern dental units have a water supply that provides coolant andrinse water to the dynamic dental instruments including the high-speedhandpiece, air/water syringe and ultrasonic scaler. This water supply isconnected to a domestic water source system. Microbiological studies ofthis water supply revealed that the water is contaminated by waterorganisms and oral flora. These organisms have been found to be massivein number and some identified as pathogenic. Dental researchists havestated that this contamination could cause infection inimmuno-suppressed patients, and cross infection may occur between dentalpatients.

Clinical tests show that oral flora is aspirated from a patient's oralcavity into the dental unit water lumens through the dynamic dentalinstruments. This revelation has prompted the Centers of Disease Controlto recommend a 20 to 30 second purge of these instruments between eachpatient appointment. The American Dental Association and The AmericanNational Standards Institute developed Specification Number 47, datedApr. 12, 1984, as the manufacturing criterion for dental unitmanufacturers. This specification requires that a means be incorporatedin the dental unit to prevent water from being drawn back beyond thepoint of the dental instrument connection. These are attempts to improvethe quality of water used for dental treatment. However, continuingresearch indicates that neither has significantly reduced contamination.

Medical studies have determined that disease incubation periods vary.Because of this variance it is difficult to make accurate assessments asto the time and place of infection. Dental treatment is frequentlysubgingival and invasive of the mucosa therefore providing a directaccess to the vascular system. It is therefore prudent to usemicrobiologically pure water for cooling and rinsing during dentaltreatment in lieu of water considered by public health standards to bepolluted and nonpotable.

Biofilms are defined as microbial masses attached to surfaces that arebathed in liquids, such as dental unit tubing. Organisms grow inorganized structures with channels in between, similar to a vascularsystem. The biofilm remains attached as water flows through the dentalunit tubing. However, some microbes in the biofilm may be periodicallyreleased into the flowing fluid where they can be transported to theoutlet of the line, e.g., the air/water syringe or spray handpiece.Examples of microbes found in dental unit water lines include species ofwaterborne pseudomonas, legionella, klebsiella, moraxella, bacillus,flavobacterium, and escheria as well as organisms common to the oralenvironment. Thus, biofilms can continually contaminate water flowingthrough a dental unit line.

SUMMARY OF THE INVENTION

The invention is directed to a water purification apparatus and waterpurification method for maintaining dental unit water quality.

The apparatus incorporates a quick connect cartridge in the water lumenof a dynamic dental instrument tubing. The cartridge has activatedcharcoal to remove chlorine from water as the water passes through thecartridge. The cartridge also contains a continuous, fixed-rate releaseiodinated resin I.sub.(n). This biocidal resin neutralizes and killsdisease causing bacteria, virus and protozoa as water flows through thecartridge. Water flowing through the resin elutes a residual iodine fromthe resin at a constant predetermined rate to maintain a purified watercondition within the dental unit water supply. A residual iodine isreleased from the resin as the water passes through the resin andremains in the water between the cartridge and the dynamic instrument.As the instrument is used aspirated oral flora are killed by theresidual iodine and are prevented from traveling back beyond thecartridge at point of use. The dental unit water line tubing isimpregnated with disinfectant to prevent biofilm from attaching to theinner surface of the tubing. This maintains a microbiologically purewater condition by preventing back growth of bacteria thus reducingcross infection potential and preventing disease transmission by way ofthe dental unit water. Quick releasable lock structures are used toconnect opposite ends of the cartridge to the water carrying tubes. Thetubes absorb iodine from the water until passivation occurs. Thisprevents microorganisms from colonizing on the tubes.

The method of preparing and maintaining a purified water conditionwithin the fluid supply system for the dental unit includes passivationof the inner surface of the dental unit tubing by circulation of anaqueous solution of saturated iodine through the tubing of the dentalunit. The saturated solution of iodine is approximately 250 ppm to 300ppm iodine. The inner surface of the plastic tubing absorbs iodine untilpassivated with iodine. The aqueous solution of saturated iodine iscirculated through the tubing for approximately thirty minutes.

The solution is then removed from the tubing and a water purificationcartridge containing means for removing chlorine from the water and acontinuous, fixed-rate release iodinated resin I.sub.(n) is installed onthe upstream end of the tubing. Water is injected through the cartridgeto treat the water by removing chlorine therefrom and to elute iodinefrom the resin into the tubing. The iodinated resin releases 4 ppm ofiodine into the water passing through the resin. Water containing theeluted iodine is retained in the tubing for approximately fifteenminutes and thereafter discharged from the tubing. When a measurableamount of iodine is discharged from the downstream end of the tubingwithout a substantial decline in the concentration of iodine in thewater the tubing is passivated. Residual iodine carried by the water iscontinuously applied to the tubing in the amount of 4 ppm iodine whichis sufficient to maintain an equilibrium of iodine moving between thetubing and the water so as to create and maintain a biostatic conditionwithin the tubing thereby resisting colonization of microorganisms onthe tubing. The purification cartridge is kept in place throughout thework day and night. At the beginning of each work day, the cartridge ischanged to maintain microbiologically pure water conditions for thatwork day period and resist microorganism colonization.

DESCRIPTION OF DRAWING

FIG. 1 is a side elevational view of a dental handpiece attached to awater supply line including a water disinfectant element or cartridge;

FIG. 2 is an enlarged sectional view taken along the line 2--2 of FIG.1;

FIG. 3 is a sectional view taken along the line 3--3 of FIG. 2;

FIG. 4 is a sectional view taken along the line 4--4 of FIG. 2;

FIG. 5 is a perspective view of the cartridge;

FIG. 6 is a top plan view of the cartridge;

FIG. 7 is an end view of the cartridge, the opposite end being a mirrorimage thereof;

FIG. 8 is a side elevational view of a dental handpiece attached to awater supply line equipped with a first water disinfectant cartridge anda water source line having a second water disinfectant cartridge;

FIG. 9 is an enlarged fragmentary top view of the second waterdisinfectant cartridge and releasable connectors attached thereto;

FIG. 10 is an enlarged side view of one end of the second waterdisinfectant cartridge and releasable connector attached thereto;

FIG. 11 is a fragmentary top side elevational view of the seconddisinfectant cartridge;

FIG. 12 is an end view of FIG. 11;

FIG. 13 is a fragmentary sectional view taken along the line 13--13 ofFIG. 11;

FIG. 14 is a sectional view taken along the line 14--14 of FIG. 13;

FIG. 15 is a sectional view taken along the line 15--15 of FIG. 10; and

FIG. 16 is a sectional view taken along the line 16--16 of FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, there is shown a dental instrument 10 having awater intake tube 13 and an air tube 12. Dental instrument 10 is shownas a dental handpiece. Dental handpiece 10 can also be an air/watersyringe, ultrasonic scaler or other dynamic dental instrument. A watersupply tube 11 leading to dental handpiece 10 includes a waterpurification and disinfectant element or cartridge of the invention,indicated generally at 20. Cartridge 20 is located in the water linebetween water tubes 11 and 13. Releasable quick connect lock structuresor fittings 37 and 38 mounted on the ends of tubes 11 and 13 are used toconnect opposite ends of cartridge 20 to tubes 11, 13. Cartridge 20treats, cleans and disinfects water passing through the cartridge andsupplies a residual disinfectant to the water that remains in the wateras it moves between cartridge 20 and dental handpiece 10. The residualdisinfectant neutralizes water contaminants that may be drawn back intothe water system for dental handpiece 10.

Water intake tube 13 is a polyurethane plastic tubing commonly used indental units. The inner surface of tube 13 absorbs residual disinfectantcarded by water as it passes through tube 13 into dental handpiece 10.Tube 13 absorbs disinfectant until the inner surface of tube 13 becomespassivated or saturated with disinfectant to prevent microbial adhesionand biofilm slime layer within tube 13. Water intake tube 13 can be madeof other materials into which antimicrobial agents can be impregnated,such as polyvinyl chloride and other polymer plastics.

Referring to FIGS. 2 to 7, cartridge 20 is a generally cylindricalmember having a housing 21 surrounding a tubular chamber 22. Cartridge20 is manufactured to retrofit the tubing of modern dental units.Cartridge chamber 22 contains a resin and/or disinfectant material 23,as seen in FIGS. 2 and 6, that functions to purify and release residualdisinfectant into water passing through cartridge 20 to kill or preventcell reproduction of water contaminants and prevent dental unit waterline contamination. This ensures that water spray 14 discharged fromhandpiece 10 is in a pure condition and contains a disinfectant therebyreducing the potential of cross infection between dental patients andpreventing disease transmission via the dental instrument water system.

Cartridge chamber 22 also contains activated charcoal 30 that functionsto remove chlorine and chlorine compounds from water entering cartridge20. As seen in FIG. 2, activated charcoal 30 is located on the waterinlet side of cartridge 20. Water flows through charcoal 30 first toremove chlorine and chlorine compounds present in the water and thenthrough disinfectant material 23. A filter or screen 25 separatescharcoal 30 from disinfectant material 23. Removing chlorine andchlorine compounds from incoming water prevents chlorine from reactingwith disinfectant and disinfectant material 23. If chlorine was notremoved from the water, the chlorine would react with the disinfectantand render the disinfectant ineffective to kill bacteria, viruses andthe like in the water. Activated charcoal 30 also removes other materialsuch as organic pollutants, suspended solids, hard water ions,trihalomethanes, PCB's, odors and offensive tastes commonly found inwater. Other materials that remove chlorine and chlorine compounds fromwater can be incorporated in cartridge 20.

For example, filter material 23 can be a purification resin containingthe polyiodide, I₅, as disclosed by Lambert and Fina in U.S. Pat. No.4,238,477, and Fina, Lambert and Bridges in U.S. Pat. No. 4,999,190. Aswater flows through cartridge 20, the iodinated resin neutralizes andextinguishes disease causing bacteria, virus, protozoa and othermicroorganisms that may be present in the water by means of a continuousrelease of iodine at a predetermined level. The resin can also be aniodinated anionic exchange resin manufactured and sold under thetrademark MCV by MCV Technologies International, Inc., of Belleville,Ill. This resin releases a specific and consistent amount of iodinewhich kills all microbial contaminants including bacteria, viruses andcysts or preventing cell reproduction rendering the contaminantharmless.

Preferably, disinfectant material 23 of cartridge 20 is an iodinatedanionic exchange resin that releases 4 ppm iodine into the water as thewater passes through cartridge 20. The water line tubing 13 downstreamfrom cartridge 20 absorbs iodine in the water until passivation of theinner surface of tube 13 occurs. A biostatic condition is created withintube 13 which prevents the problem of biofilm and back growth ofbacteria aspirated into the tubing. The continuous release of 4 ppmiodine into the water from disinfectant material 23 maintains anequilibrium between the passivated tubing 13 and the water. In addition,the passivated condition of tubing 13 is maintained by the continuousrelease of 4 ppm iodine into the water which resists microorganisms fromcolonization on the tubing. Iodine remains as a residual in the waterline between cartridge 20 and dental handpiece 10. Aspirated oral floraand other contaminants are destroyed by the residual iodine in the waterand are prevented from traveling back beyond cartridge 20. Thismaintains a microbiologically pure water condition and prevents diseasetransmission through the handpiece water system with subsequent use ofhandpiece 10. Other types of resins and neutralizing agents can be usedas disinfectant material 23 for cartridge 20. For example otherhalogens, disinfectants and pesticides can be used instead of iodine.

Disinfectant material 23 and activated charcoal 30 are held withinchamber 22 by a pair of transverse filter members 24 and 26 located atopposite ends of chamber 22. Filter member 25 separates activatedcharcoal 30 from disinfectant material 23. Filter members 24 to 26 havea circular shape with a plurality of relatively small openings in theform of a filter material, as seen in FIGS. 4 and 7, to allow passage ofwater through cartridge 20 while retaining disinfectant material 23 andactivated charcoal 30 within chamber 22. Other shapes and openingpatterns may be used to construct filter members 24 to 26. Filtermembers 24 to 26 have a tight fit relationship with the inside surfaceof housing 21. Housing 21 has end walls 27 and 32 located adjacent theouter peripheral surfaces of filter members 24, 26, respectively. Endwall 27 has a centrally located passage 31 surrounded by an outwardlyextended tubular collar 28. The diameter of passage 31 is less than thediameter of filter member 24. Water enters cartridge 20 through passage31 from water supply tube 11 and flows through filter member 24 andactivated charcoal 30 for chlorine removal treatment and thendisinfectant material 23 for purification. The outer end of collar 28has an annular flange 29 with a threaded outer surface, as shown in FIG.5, that cooperates with a threaded fitting 37 to releasably connect end27 of cartridge 20 to water supply tube 11.

Similarly, end wall 32 of cartridge 20 has a central passage 36surrounded by an outwardly extended tubular collar 33. The diameter offilter member 26 is greater than the diameter of passage 36. Waterenters cartridge 20 through passage 31 from water supply tube 11, flowsthrough filter member 24, activated charcoal 30, disinfectant material23 and then out filter member 26 and passage 36 into water intake tube13 connected to dental instrument 10. Water flowing through passage 36is in a microbiologically purified condition and contains a residualdisinfectant that maintains an equilibrium of disinfectant movingbetween water intake tube 13, when passivated with the disinfectant, andthe water to resist microorganism colonization and biofilm on tube 13.Disinfectant also remains in water spray 14 to destroy aspirated oralflora and other contaminants that may be drawn back into the dental unitwater system. The outer end of collar 33 has an annular flange 34 with athreaded outer surface, as shown in FIG. 5, that cooperates with asecond threaded fitting 38 to releasably connect cartridge 20 with waterintake tube 13.

Referring to FIG. 2, fitting 37 has a generally tubular body 39 havingan internal passage 46. A ring 41 surrounding inner end 49 of body 39has an inwardly directed wall 48 attached to body 39. Collar 28 ofcartridge 20 telescopes into ring 41 and surrounds inner end 49 of body39. The inside surface of ring 41 has threads 42 that accommodatethreads on the outer surface of flange 29 to releasably hold fitting 37on cartridge 20. The outer end of ring 41 has an inwardly projecting lip43 that engages the outer surface of collar 28. The top surface of lip43 is located adjacent end wall 27 of cartridge 20 when the outerthreaded surface of flange 29 is tightly threaded on threads 42 offitting 37. Inner end 49 of body 39 is located in passage 31. End 49 isslightly tapered to facilitate insertion thereof into passage 31.

As shown in FIG. 2, the outer diameter of body 39 increases to adiameter that is substantially the same as the diameter of passage 31.This prevents water from leaking between water supply line 11 andcartridge 20. Outer end 47 of body 39 is inserted into the passage ofwater supply tube 11. End 47 has a tapered outer surface to facilitateinsertion of end 47 into the passage of water supply tube 11. Fitting 37has a foot 44 located adjacent end 47 to prevent fitting 37 frominadvertently slipping out of water supply tube 11. The outer surface ofbody 39 diverges outwardly to form foot 44. The diameter of foot 44 isslightly larger than the diameter of the passage in water supply tube 11thereby expanding water supply tube 11 when body 39 is located in thetube passage to provide holding action. The middle portion of body 39also diverges outwardly to an increased diameter, as seen in FIG. 2, toprovide additional holding action. The end of water supply tube 11engages wall 48 when fitting 37 is fully inserted into the passage ofwater supply tube 11.

Fitting 38 has substantially the same structure as fitting 37. Fitting38 has a tubular body 50 with an internal passage 56. A ring 51surrounds inner end 59 of body 50. Ring 51 has an inwardly directed wall58 secured to body 50. Collar 33 of cartridge 20 telescopes into ring 51and surrounds inner end 59 of body 50. The inside surface of ring 51 hasa plurality of threads 52 that accommodate threads on the outer surfaceof flange 34 to releasably hold fitting 38 on cartridge 20. Ring 51 hasa lip 53 that engages the outer surface of collar 33. The top surface oflip 53 is located adjacent end wall 32 of cartridge 20 when the outerthreaded surface of flange 34 is tightly threaded on threads 52 offitting 38. Ends 57 and 59 of body 50 have tapered outer surfaces tofacilitate insertion thereof into the passage of water intake tube 13and cartridge passage 36, respectively. Fitting 38 has a foot 54 locatedadjacent end 57 that engages the lumen of water intake tube 13 toprevent fitting 38 from inadvertently slipping out of water intake tube13, as seen in FIG. 2.

In use, water intake tube 13 leading to dental handpiece 10 or otherdynamic dental instrument is passivated or saturated with disinfectant,such as iodine. A method to reach saturation quickly includescirculating an aqueous solution of saturated disinfectant through tube13 for approximately thirty minutes. Tube 13 is a polyurethane plastictubing that absorbs disinfectant from the saturated solution circulatingtherein. Other types of absorbent tubing can be used with dentalhandpiece 10. An aqueous saturated solution of iodine has 250 ppm to 300ppm iodine depending on the temperature of the solution. The saturatedsolution of disinfectant is then removed from tube 13. Cartridge 20 isinserted between water supply tube 11 and water intake tube 13. Fittings37 and 38 mounted on the ends of tubes 11 and 13 releasably lockopposite ends of cartridge 20 onto the downstream end of tube 11 and theupstream end of tube 13. Outer threaded surfaces of cartridge flanges 29and 34 engage threaded inner surfaces 42 and 52 of fittings 37 and 38 toreleasably hold the cartridge on water tubes 11 and 13.

Water eluting disinfectant from cartridge 20 is then injected throughcartridge 20 into tube 13 and retained within tube 13 for approximatelyfifteen minutes. After fifteen minutes of retention within tube 13, thewater and disinfectant are discharged from the tube. When measurableamounts of disinfectant can be discharged from the downstream end oftube 13 without a substantial decrease in disinfectant concentration,the inner surface of water intake tube 13 is passivated withdisinfectant.

Cartridge 20 contains disinfectant material 23 that purifies and addsresidual disinfectant to water supplied to tube 13 passivated withdisinfectant and dental handpiece 10. Water passing through cartridge 20elutes disinfectant from disinfectant material 23 at a continuousfixed-rate, such as 4 ppm iodine. Cartridge 20 also contains activatedcharcoal 30 to remove chlorine and chlorine compounds from the waterprevent chlorine reaction with the disinfectant. Continuously injectingwater containing disinfectant eluted from disinfectant material 23 intopassivated tube 13 maintains an equilibrium of disinfectant movingbetween tube 13 and the water passing through tube 13 as well asmaintaining the passivated condition of tube 13. Impregnation of tube 13with disinfectant resists biofilm proliferation. The residualdisinfectant also destroys contaminants and disease causingmicroorganisms when they are drawn back into the water line. Thismaintains a microbiologically pure water system for dental handpiece 10preventing cross infection between dental patients. Filter members 24 to26 contained within chamber 22 of cartridge 20 prevent passage ofdisinfectant material 23 and activated charcoal 30 from cartridge 20and, in addition, filter particulates, bacteria, viruses and protozoa.

A water purification cartridge 20 is retained on water intake tube 13after tube 13 has reached the passivated condition to continuously bathethe inner surface of tube 13 in aqueous disinfectant solution, such as asolution of 4 ppm iodine. At the beginning of each work day cartridge 20is removed and replaced with a new cartridge. The threaded surfaces ofcartridge flanges 29 and 34 and threaded fitting surfaces 42 and 52 areseparated to quickly remove cartridge 20 from fittings 37 and 38 securedto tubes 11 and 13. Cartridge 20 is discarded and then the opposite endsof the new cartridge are quickly connected to fittings 37 and 38.Retaining a water purification cartridge on the upstream end of tube 13maintains the passivated condition of tube 13. By keeping the innersurface of tube 13 saturated with disinfectant a biostatic condition iscreated within tube 13 which resists microorganisms from colonization ontube. The microbiologically pure water condition of the dental unitwater system is preserved thereby preventing cross-contamination duringsubsequent use of handpiece 10.

Referring to FIGS. 8 to 16, there is shown a modified dental instrument100 having a water intake tube 113 and an air tube 112. Dentalinstrument 100 is substantially the same as dental handpiece 10 shown inFIG. 1 and described above. Dental instrument 100 can also be anair/water syringe, ultrasonic scaler or other dynamic dental instrument.A water supply tube 111 leading to dental instrument 100 is releasablycoupled to a first water disinfectant cartridge of the inventionindicated generally at 120 and a second water disinfectant cartridge ofthe invention indicated generally at 122. Cartridges 120 and 122 treat,clean and disinfect water passing through cartridges 120 and 122 andsupply a residual disinfectant to the water. The residual disinfectantremains in the water as it moves through tubes 111 and 113 into dentalinstrument 100.

Tubes 111 and 113 are polyurethane plastic tubing customarily used indental units. The inner surfaces of tubes 111 and 113 absorb residualdisinfectant carried by water as the water passes through tubes 111 and113 into dental instrument 100. Tubes 111 and 113 absorb disinfectantuntil the inner surface of each tube 111, 113 becomes passivated orsaturated with disinfectant. The disinfectant incorporated into theinner surfaces of tubes 111 and 113 prevents microbial adhesion andresist biofilm slime layer formation within the tubes. Tubes 111 and 113can be made of other materials into which antimicrobial agents can beimpregnated, such as polyvinyl chloride and other polymer plastics.

The residual disinfectant eluted from cartridges 120 and 122 neutralizeswater contaminants that may be drawn back into the water system fordental instrument 100 and neutralizes water contaminants originatingfrom the domestic or community water supply system whereby water spray114 discharged from the dental instrument is in a pure condition andcontains a disinfectant. Continuously applying disinfectant within tubes111 and 113 maintains the passivated condition of the tubes and createsa biostatic condition within tubes 111 and 113 which resistsmicroorganisms from colonization on the tubes. This reduces thepotential of cross infection between dental patients and preventsdisease transmission via the dental instrument water system or thedomestic water supply system.

Referring to FIG. 8, cartridge 120 is located in the water line betweenwater tubes 111 and 113. Releasable quick connect fittings 137 and 138mounted on the ends of tubes 111 and 113 are used to connect oppositeends of cartridge 120 to tubes 111 and 113. Cartridge 120 contains aresin or disinfectant material (not shown) substantially similar toresin 23 of cartridge 20 that functions to filter, purify and releaseresidual disinfectant into water passing through the cartridge to killor prevent cell reproduction of water contaminants. Cartridge 120 isused to provide microbiological pure water to the dental unit and toprevent back contamination to the water supply system. Fittings 137 and138 are identical to fittings 37 and 38 shown in FIG. 2. The ends ofcartridge 120 are threaded into fittings 137 and 138 to releasably holdthe fittings 137 and 138 on cartridge 120. The outer end of fitting 137is inserted into the passage of water supply tube 111. The outer end offitting 138 is inserted into the passage of water intake tube 113.Fittings 137 and 138 releasably lock opposite ends of cartridge 120 ontothe ends of tubes 111 and 113.

A second water disinfectant cartridge 122 is located in the water linebetween water supply tube 111 and a water source tube 121. Cartridge 122is installed in the dental instrument water system at the point ofconnection to self contained water system or a domestic water supplysystem which reinforces and/or replaces a domestic or communitypurification system. Cartridge 122 can be used at geographic locationswhere a domestic or community water purification system does not existor is inadequate. Releasable connectors 157 and 158 mounted on the endsof tubes 111 and 121 connect opposite ends of cartridge 122 to tubes 111and 121.

Referring to FIGS. 9 to 16, cartridge 122 is a generally cylindricalmember having a housing 123 surrounding a tubular chamber 124. Chamber124 contains a disinfectant material 126 and filter members 127 and 128,as seen in FIG. 13. Disinfectant material 126 is the same as thedisinfectant material contained in cartridge 120 and disinfectantmaterial 23 in cartridge 20. Disinfectant material 126 purifies waterfrom community water supply line 121 and releases residual disinfectantinto water passing through cartridge 122 to kill or eliminate cellreproduction of water contaminants and tubing biofilm. This reduces thepotential or cross infection between dental patients and preventsdisease transmission via the dental instrument water system or thedomestic water supply system.

Cartridge chamber 124 also contains activated charcoal 130 for removingchlorine and chlorine compounds from chlorinated water enteringcartridge 122. As shown in FIG. 13, activated charcoal 130 is located onthe water inlet side of cartridge 122. Water flows through charcoal 130first to remove chlorine and chlorine compounds from the water and thenthrough disinfectant material 126. A filter or screen 125 separatescharcoal 130 from disinfectant material 126. Removing chlorine from thewater prevents chlorine reaction with disinfectant released fromcartridges 120 and 122 so that the disinfectant is not ineffective tokill bacteria, viruses and the like. Activated charcoal 130 also removesother water contaminants from incoming water. Other materials thatremove chlorine and chlorine compounds from water can be used withcartridge 122.

Disinfectant material 126 of cartridge 122 and the disinfectant materialcontained in cartridge 120 can be resins containing the polyiodide, I₅,as disclosed in U.S. Pat. Nos. 4,238,477 and 4,999,190. As water flowsthrough cartridges 120 and 122 a continuous fixed-rate release of iodineat a predetermined level from the iodinated resins neutralizes andextinguishes disease causing agents, such as bacteria, viruses, protozoaand other microorganisms that may be present in the dental instrumentwater system or the domestic water supply system. The resins can also beiodinated anionic exchange resins manufactured and sold under thetrademark MCV by MCV Technologies International, Inc., of Belleville,Ill. These resins release a specified and consistent amount of iodinewhich kills all microbial contaminants, such as bacteria, viruses andcysts in the dental instrument water system and the domestic watersupply system or prevents reproduction of cells rendering thecontaminants harmless.

Preferably, the disinfectant material of cartridge 120 and disinfectantmaterial 126 of cartridge 122 are iodinated anionic exchange resins thatrelease 4 ppm iodine into the water as it passes through cartridges 120and 122. The water line tubing 111 and 113 downstream from cartridges120 and 122 absorb iodine in the water until passivation of the innersurfaces of tubes 111 and 113 occurs. A biostatic condition is createdwithin tubes 111 and 113 which prevents biofilm proliferation and backgrowth of bacteria aspirated into the tubing. The continuous release of4 ppm iodine into the water from the disinfectant material of cartridges120 and 122 maintains an equilibrium of iodine moving between thepassivated surfaces of tubes 111 and 113 and the water flowing throughthe tubes. In addition, the passivated condition of tubes 111 and 113 ismaintained by the continuous fixed-rate release of iodine into the waterthereby resisting microorganism colonization on the tubing. Iodineremains as a residual in the water line between cartridge 122 andcartridge 120 and between cartridge 120 and dental instrument 100.Aspirated oral flora and other contaminants in the dental instrumentwater or the domestic water supply systems are destroyed by the residualiodine remaining in the water. This maintains a microbiologically purewater condition and purifies water supplied from the domestic watersupply system. Other types of resins and neutralizing agents can be usedas the disinfectant material for cartridges 120 and 122, such asdisinfectant material containing other halogens, disinfectant andpesticides.

Disinfectant material 126 and activated charcoal 130 are held in chamber124 with filters 127 and 128 located at opposite ends of chamber 124.Filter 125 separates activated charcoal 130 from disinfectant material126. Filters 125, 127 and 128 allow passage of water through cartridge122 while retaining disinfectant material 126 and activated charcoal 130within chamber 124. Filters 127 and 128 fit tightly into housing 123.End wall 129 has a centrally located passage 131 surrounded by outwardlyextended collar 132 having a generally tubular body 139. As shown inFIG. 13, passage 131 has a reduced diameter outer section 133 incommunication with end openings or ports 134. Water enters cartridge 122through ports 134 from water source tube 12 1 and flows through passage131 through filter 127 and activated charcoal 130 for chlorine removaltreatment and then through disinfectant material 126 for purification.The inner end of collar body 139 has a channel-shaped annular groove 136that cooperates with a fastener or lever 173 of connector 157 toreleasably connect end 129 of cartridge 122 to water source tube 121. Asecond annular groove 141 in body 139 spaced outwardly from groove 136accommodates an O-ring or seal 142. The seal 142 prevents water leakagefrom the flow path 167 of connector 157 when connector 157 is coupled tocollar 132. Outer end 143 of body 139 has a reduced outer diameterwhereby end 143 can be inserted into inner chamber 163 of connector 157,as shown in FIG. 16.

Referring to FIG. 13, end wall 144 of cartridge 122 has a centralpassage 146 surrounded by an outwardly directed collar 147 having agenerally tubular body 152. Passage 146 has a reduced diameter outersection 148 that communicates with ports 149. Water flows throughpassage 146 and moves out of cartridge 122 through ports 149 into tube111 connected to cartridge 120. Water flowing through ports 149 intotube 111 is in a microbiologically purified condition and contains aresidual disinfectant that maintains an equilibrium of disinfectantmoving between the inner surfaces of water tubes 111 and 113, whenpassivated, and the water flowing through tubes 111 and 113 to resistmicroorganism colonization and biofilm slime layers on tubes 111 and113. Disinfectant also remains in the water to kill or prevent watercontaminant cell reproduction. Cartridge 122 is used to providemicrobiologically pure water to the dental unit and to prevent backcontamination to the water supply system. In this manner cartridge 122reinforces existing purification systems or takes the place of adomestic or community purification system at geographic locations wheresuch a purification system is non-existent. The inner end of body 152has an annular groove 151 that accommodates and cooperates with a lever174 of connector 158 to quickly releasably connect and disconnectcartridge end 144 to and from the end of water supply tube 111. AnO-ring seal 154 located in a second annular groove 153 in body 152prevents water leakage from connector 158 when connector 158 is fittedon collar 147. The outer end of collar body 152 has a reduced diameterso that end 156 can be moved into the inner chamber of connector 158.

Referring to FIG. 16, connector 157 has a generally cylindrical body 162that surrounds inner chamber 163. Connector body 162 has an outerthreaded surface that cooperates with inner threaded surfaces ofconnector members 159 and 161 to hold members 159 and 161 on connectorbody 162. Connector members 159 and 161 are cup-shaped members havingopen tops. Members 159 and 161 are mounted on connector body 162 wherebytheir respective open tops are orientated toward each other. Connectormember 161 is secured directly to the end of tube 121. An annular sealor washer 168 is located between connector body 162 and connector member161 to eliminate water leakage from flow path 167. Each of connectormembers 159 and 161 and connector body 162 has a centrally locatedbottom opening to form a flow path 167 for water to move through chamber163 and connector 157 and into cartridge 122. A spring 164 located inchamber 163 biases a ball or bead 166 into engagement with bottom wall169 of connector member 159 to close the opening in wall 169 and blockflow path 167. When reduced diameter end 143 of cartridge collar 132 isinserted through the opening in wall 169, bead 166 is moved away fromwall 169 to open flow path 167 placing ports 134 inside chamber 163 ofconnector 157 and in communication with the passage of water source tube121.

Connector member 159 has an annular flange 171 that receives andsurrounds collar 132 of cartridge 122. Seal 142 fits into a annulargroove 172 in flange 171 adjacent wall 169 to prevent leakage of waterbetween connector 157 and cartridge 122. A groove 179 adjacent the outerend of connector flange 171 accommodates lever 173 that functions toreleasably couple cartridge collar 132 to connector 157. Collar end 143engages spring-biased bead 166 to hold bead 166 in the open position andallow water to flow into cartridge 122 for filtration throughdisinfectant material 126.

Referring to FIGS. 10 and 15, lever 173 is a generallyrectangular-shaped plate slidably mounted in groove 179 of connectorflange 171. The upper and lower ends of lever 173 are turned inwardly toform tabs or stops 176 and 177. Stops 176 and 177 engage connectorflange 171 to limit vertical movement of lever 173 between coupled anduncoupled positions. As shown in FIG. 15, lever 173 has a center opening178 having a smaller diameter top portion and a larger diameter bottomportion. Lever 173 is moved downwardly to position collar 132 in the topportion of opening 178 and releasably lock cartridge collar 132 toconnector 157. The top portion of opening 178 encircles collar 132 andthe top half of lever 173 fits into groove 136 of cartridge collar 132.The diameter of the top portion of opening 178 is substantially the sameas the diameter of collar 132 at groove 136. When lever 173 is movedupwardly, the bottom portion of opening 178 is located adjacent andtelescopes around collar 132 whereby collar 132 can be unplugged andremoved from connector 157. The outer diameter of cartridge collar 132is less than the diameter of the bottom portion of opening 178 so thatcollar 132 can be quickly and easily moved in and out of connector 157.

Connector 158 has substantially the same structure as connector 157. Asshown in FIG. 9, connector 158 is secured directly to the end of watersupply tube 111. Connector 158 has an annular flange that receives andsurrounds collar 152 of cartridge 122. When reduced diameter section 156of collar 152 is inserted into connector 158, a spring-biased valve,identical to bead valve 166 of connector 157, contained within connector158 is moved to the open position whereby ports 149 are positionedinside the inner chamber of connector 158 and in communication with thepassage of water supply tube 111. Connector 158 has a lever 174 slidablymounted for longitudinal movement relative to the lateral extension ofconnector 158. Lever 174 releasably couples cartridge collar 152 toconnector 158 whereby purified water containing a residual disinfectantflows into tube 111 from cartridge 122.

Lever 174 is a generally rectangular-shaped plate having inwardly turnedends that engage the outer surface of connector 158 thereby limitingvertical movement of lever 174 between coupled and uncoupled positions.Lever 174 is moved downwardly into groove 151 of cartridge collar 152 toreleasably lock collar 152 to connector 158 and tube 111. When lever 174is moved upwardly, collar 152 can be unplugged and removed fromconnector 158.

In use, water supply tube 111 and water intake tube 113 leading todental instrument 100 are passivated with disinfectant, such as iodine.A method to reach passivation quickly includes an aqueous solution ofsaturated disinfectant circulated through tubes 111 and 113 forapproximately thirty minutes. Tubes 111 and 113 are polyurethane plastictubes that absorb disinfectant from the saturated solution circulatingtherein. Other types of absorbent tubing, such as PVC and polymerplastic tubing, can be used with dental instrument 100. After thirtyminutes of circulation, the saturated solution is removed from tubes 111and 113. Cartridge 120 is inserted between water supply tube 111 andwater intake tube 113 that leads to dental instrument 100. Fittings 137and 138 mounted on the ends of tubes 111 and 113 releasably lockopposite ends of cartridge 120 onto the ends of tubes 111 and 113.Cartridge 122 is inserted between water source tube 121 and water supplytube 111 adjacent the point of connection to a domestic or communitypurification system. Connectors 157 and 158 secured to the ends of tubes121 and 111, respectively, releasably couple opposite ends 129 and 144of cartridge 122 onto the ends of tubes 121 and 111. Plugging cartridgecollars 132 and 152 into connectors 157 and 158 moves spring-biasedvalves 166 to the open position allowing water to flow through cartridge122. Levers 173 and 174 are moved downwardly into grooves 136 and 151 ofcartridge collars 132 and 152 to releasably lock the collars ofcartridge 122 to connectors 157 and 158 and tubes 121 and 111.

Water eluting disinfectant from cartridges 120 and 122 is then injectedthrough the cartridges into tubes 111 and 113 and retained therein forapproximately fifteen minutes. As water passes through cartridge 122,chlorine and chlorine compounds are removed from the water by activatedcharcoal 130. After fifteen minutes has elapsed, the water/disinfectantsolution is discharged from tubes 111 and 113. When measurable amountsof disinfectant can be discharged from the downstream ends of tubes 111and 113 without a substantial decrease in disinfectant concentration,the interior surfaces of water tubes 111 and 113 are passivated withdisinfectant.

The disinfectant material contained within cartridge 120 purifies waterflowing through the cartridge 120 and adds residual disinfectant to thewater supplied to tube 111 passivated with disinfectant and dentalinstrument 100. Water passing through cartridge 120 elutes disinfectantfrom the disinfectant material contained therein at a continuousfixed-rate, such as 4 ppm iodine. Continuously injecting watercontaining eluted disinfectant into passivated tube 111 maintains anequilibrium of disinfectant moving between tube 111 and the waterpassing through tube 111 as well as maintaining the passivated conditionof tube 111. The residual disinfectant in the water also prevents backcontamination beyond cartridge 120. Similarly, disinfectant material 126contained within cartridge chamber 124 neutralizes and kills diseasecausing bacteria, viruses and other agents in the water as the waterpasses through cartridge 122 from water source tube 121. Cartridge 122also contains activated charcoal that removes chlorine and chlorinecompounds from water entering cartridge 122 thereby preventing chlorinefrom reacting with the disinfectant rendering the disinfectantineffective. Residual disinfectant eluted from disinfectant material 126into the water at a constant predetermined rate maintains a purifiedwater condition and maintains an equilibrium of disinfectant movingbetween tube 113 and the water therein as well as the passivatedcondition of tube 113. Impregnation of tubes 111 and 113 withdisinfectant creates a biostatic condition within the tubes whichresists biofilm proliferation. Cartridges 120 and 122 preserve amicrobiologically pure water system for dental instrument 100 andprevent cross infection between dental patients and back flow ofcontamination to water supply systems.

Water purification cartridges 120 and 122 are retained on water tubes111, 113 and 121 after tubes 111 and 113 have been passivated withdisinfectant so as to continuously bathe the inner surfaces of tubes 111and 113 in aqueous disinfectant solution, such as a solution of 4 ppmiodine. At the beginning of each work day cartridge 120 is removed fromthe water line and replaced with a new cartridge. Cartridge 122 isreplaced on a less frequent basis which is determined by the cartridgesize. Fittings 137 and 138 and connectors 157 and 158 provide quick andeasy disconnection and connection of cartridges 120 and 122 to the waterline. Retaining water purification cartridges on the upstream ends oftubes 111 and 113 maintains the passivated condition of tubes 111 and113. By keeping the inner surfaces of tubes 111 and 113 saturated withdisinfectant a biostatic condition is created within tubes 111 and 113to resist microorganism colonization and biofilm. This ensures acontinuous microbiologically pure water condition and provides forcontrol of water contaminants that may be drawn back into the watersystem for dental instrument 100.

While there has been shown and described preferred embodiments of thewater purification apparatus, it is understood that changes in materialsand structures can be made by those skilled in the art without departingfrom the invention. The invention is defined in the following claims.

We claim:
 1. A dental apparatus having a fluid supply system connectedto a fluid source system comprising: a dental instrument having firsttube means, second tube means receiving fluid from the first tube means,fluid purification means releasably mounted on the first tube means andthe second tube means, the fluid purification means including filtermeans and disinfectant means operable to treat, filter, purify andsupply a disinfectant to the fluid as the fluid passes through thedisinfectant means, the second tube means having an inner surfacepassivated with the disinfectant to create and maintain a biostaticequilibrium of the disinfectant moving between the inner surface of thesecond tube means and the fluid flowing through the second tube means,the disinfectant remaining as a residual in the fluid as the fluid movesthrough the second tube means and the dental instrument whereby when thefluid is discharged from the dental instrument the fluid is in amicrobiologically pure condition and contains the disinfectant, thedisinfectant neutralizing contaminants drawn back into the fluid supplysystem and resisting colonization of microorganisms on the inner surfaceof the second tube means with the purification means preventingaspirated contaminants from traveling back beyond the purification meansto prevent cross infection, and means connected to the first tube meansand second tube means to releasably attach the fluid purification meansto the first and second tube means.
 2. The apparatus of claim 1 wherein:the fluid purification means has chamber means, the disinfectant meanslocated in the chamber means.
 3. The apparatus of claim 1 wherein: thefluid purification means has coupling means located on outer endsthereof.
 4. The apparatus of claim 1 wherein: the filter means islocated adjacent ends of the disinfectant means to retain thedisinfectant means within the fluid purification means as fluid flowsthrough the fluid purification means.
 5. The apparatus of claim 1wherein: the fluid purification means comprises a cartridge having ahousing defining a chamber, the housing having opposite ends, each endhaving a passage open to the chamber, the filter means located in thechamber.
 6. The apparatus of claim 5 wherein: the cartridge has collarmeans attached to each end, the collar means cooperating with the meansconnected to the first tube means and second tube means to releasablyattach the cartridge to the first and second tube means.
 7. Theapparatus of claim 1 wherein: the fluid purification means includescollar means cooperating with the means connected to the first tubemeans and second tube means to releasably attach the fluid purificationmeans to the first and second tube means.
 8. The apparatus of claim 1wherein: the fluid purification means includes means operable to removechlorine and chlorine compounds from the fluid as the fluid flowsthrough the fluid purification means.
 9. The apparatus of claim 1wherein: the disinfectant means is an iodinated anionic exchange resin.10. The apparatus of claim 1 wherein: the disinfectant means is a resincontaining a continuous, fixed-rate release iodinated resin I.sub.(n).11. The apparatus of claim 1 wherein: the disinfectant is a specifiedand consistent amount of iodine released from the disinfectant meansinto the fluid as the fluid passes through the disinfectant means so asto kill microbial contaminants or prevent cell reproduction and tubingbiofilm rendering the contaminants harmless.
 12. A dental apparatushaving a fluid supply system connected to a fluid source systemcomprising: a dental instrument having first tube means connected to thefluid source system, second tube means receiving fluid from the firsttube means, third tube means receiving fluid from the second tube means,first fluid purification means releasably mounted on the first tubemeans and the second tube means, second fluid purification meansreleasably mounted on the second tube means opposite from the firstfluid purification means and third tube means, the first and secondfluid purification means each including filter means and disinfectantmeans operable to treat, filter, purify and supply a disinfectant to thefluid as the fluid passes through the disinfectant means, the second andthird tube means each having an inner surface passivated with thedisinfectant to create and maintain a biostatic equilibrium of thedisinfectant moving between the inner surfaces of the second and thirdtube means and the fluid flowing through the second and third tubemeans, the disinfectant remaining as a residual in the fluid as thefluid moves through the second and third tube means and the dentalinstrument and is discharged from the dental instrument to maintain apurified water condition within the fluid supply system for the dentalinstrument whereby when the fluid is discharged from the dentalinstrument the fluid is in a microbiologically pure condition andcontains the disinfectant, the disinfectant neutralizing contaminantsdrawn back into the fluid supply system and resisting colonization ofmicroorganisms on the inner surfaces of the second and third tube meanswith the purification means preventing aspirated contaminants fromtraveling back beyond the purification means to prevent cross infection,first means connected to the first tube means and second tube means toreleasably attach the first fluid purification means to the first andsecond tube means, and second means connected to the second tube meansand third tube means to releasably attach the second fluid purificationmeans to the second and third tube means.
 13. The apparatus of claim 12wherein: the first and second fluid purification means each has chambermeans, the disinfectant means located in the chamber means.
 14. Theapparatus of claim 12 wherein: the first and second fluid purificationmeans each has coupling means located on outer ends thereof.
 15. Theapparatus of claim 12 wherein: the filter means is located adjacent endsof the disinfectant means to retain the disinfectant means within thefluid purification means as fluid flows through the fluid purificationmeans.
 16. The apparatus of claim 12 wherein: the first and second fluidpurification means each comprises a cartridge having a housing defininga chamber, the housing having opposite ends, each end having a passageopen to the chamber, the filter means located in the chamber.
 17. Theapparatus of claim 12 wherein: the first fluid purification meansincludes collar means having groove means open to an outer surface ofthe collar means, the groove means cooperating with the first means toreleasably couple the first fluid purification means to the first andsecond tube means.
 18. The apparatus of claim 12 wherein: the secondfluid purification means includes collar means cooperating with thesecond means to releasably attach the second fluid purification means tothe second and third tube means.
 19. The apparatus of claim 12 wherein:the first fluid purification means includes means operable to removechlorine and chlorine compounds from the fluid as the fluid flowsthrough the first fluid purification means.
 20. The apparatus of claim12 wherein: the means operable to remove chlorine and chlorine compoundsfrom the fluid comprises a resin containing activated charcoal locatedon a water intake end of the first fluid purification means.
 21. Theapparatus of claim 12 wherein: the disinfectant means is an iodinatedanionic exchange resin.
 22. The apparatus of claim 12 wherein: thedisinfectant means is a resin containing a continuous, fixed-raterelease iodinated resin I.sub.(n).
 23. The apparatus of claim 12wherein: the disinfectant is a specified and consistent amount of iodinereleased from the disinfectant means into the fluid as the fluid passesthrough the disinfectant means so as to kill microbial contaminants orprevent cell reproduction and tubing biofilm rendering the contaminantsharmless.
 24. The apparatus of claim 12 wherein: the first fluidpurification means is located adjacent a point of connection of thefluid supply system to the fluid source system, and the second fluidpurification means being located adjacent a point of connection of thefluid supply system to the dental instrument.
 25. The apparatus of claim12 wherein: the second tube means and third tube means each is apolyurethane plastic tubing.
 26. A method of passivating an innersurface of tubing for a dental unit with a disinfectant to create apurified water condition within a fluid supply system for the dentalunit and resist colonization of microorganisms on the inner surface ofthe tubing: circulating a solution saturated with the disinfectantthrough the tubing whereby the disinfectant is absorbed by the innersurface of the tubing, removing the solution from the tubing andinstalling a water purification cartridge operable to supply thedisinfectant to water passing through the cartridge on an upstream endof the tubing, treating water to remove chlorine therefrom, injectingwater through the cartridge into the tubing to elute the disinfectantfrom the cartridge, retaining water and disinfectant eluted from thecartridge within the tubing until measurable amounts of the disinfectantcan be discharged from a downstream end of the tubing without asubstantial decline in the concentration of the disinfectant in thewater.
 27. The method of claim 26 wherein: the solution is circulatedthrough the tubing for thirty minutes.
 28. The method of claim 26wherein: water and the disinfectant eluted from the water purificationcartridge are retained in the tubing for fifteen minutes.
 29. The methodof claim 26 wherein: the disinfectant is iodine.
 30. The method of claim26 wherein: the water purification cartridge includes a continuous,fixed-rate release iodinated resin I.sub.(n).
 31. The method of claim 30wherein: the water purification cartridge releases 4 ppm iodine into thewater passing through the resin.
 32. The method of claim 26 wherein: thewater purification cartridge includes means operable to remove chlorineand chlorine compounds from the water as the water flows through thecartridge.
 33. The method of claim 26 wherein: the tubing is apolyurethane plastic tubing.
 34. A method of maintaining passivation ofan inner surface of dental unit tubing with a disinfectant to maintain apurified water condition within a fluid supply system for the dentalunit and resist colonization of microorganisms on the inner surface ofthe tubing: passivating the inner surface of the tubing with thedisinfectant, installing a water purification cartridge operable tosupply the disinfectant to water passing through the cartridge on anupstream end of the tubing, treating water to remove chlorine therefrom,continuously applying water containing disinfectant eluted from thecartridge at a fixed-rate to maintain an equilibrium of the disinfectantmoving between the inner surface of the tubing and the water movingthrough the tubing thereby maintaining the passivated condition of theinner surface of the tubing and creating and maintaining a biostaticcondition within the tubing.
 35. The method of claim 34 wherein: thedisinfectant is iodine.
 36. The method of claim 34 wherein: the waterpurification cartridge includes a continuous, fixed-rate releaseiodinated resin I.sub.(n).
 37. The method of claim 36 wherein: the waterpurification cartridge releases 4 ppm iodine into the water passingthrough the resin.
 38. The method of claim 34 wherein: the waterpurification cartridge includes means operable to remove chlorine andchlorine compounds from the water as the water flows through thecartridge.
 39. The method of claim 34 wherein: the tubing is apolyurethane plastic tubing.